Solar energy is one of the fastest growing renewable energy sources mainly because sunlight is the most abundant source of energy and is unlimited, clean and free. The major advantage of solar energy is the transformation of energy with zero carbon dioxide (CO2) emissions. However, the main drawback is that the energy source is intermittent in nature since it strongly depends on the weather conditions. In order to overcome this limitation, energy storage elements are often required in order to provide a constant power source.
Multi-input converters (MIC) topologies address the issue of interconnecting several energy sources with a single power converter. The conventional approach to implement multi-input power systems is to interconnect the elements using different series or parallel connected power converters. However, the disadvantages are low power density and efficiency due to multiple conversions stages. The solution is to implement a multipart converter, which can interface with renewable energy sources, storage elements and loads.
Recently introduced three-port converter (TPC) topologies are based on reduced energy processing and shared components and claim to achieve high efficiency and power density. TPCs can be said to have fewer conversion stages and generally higher efficiency compared to solutions employing several independent two-port converters. However, in TPCs it is required to add extra switches to provide controllability and/or diodes to configure the power flow paths. TPC topologies need a high number of semiconductors.
FIG. 1 shows the concept of a conventional three-port converter. The three-port converter has an input voltage port, a battery port, and a load, to which power is delivered.